code: def test_num_envs(self):
      assert self.vec_env.num_envs == self.num_envs
  
file_path: pfrl/tests/envs_tests/test_vector_envs.py
imports: import gym
  import numpy
  import pytest
  import pfrl
label_desc: Use image node_id 3 for calling the TestSerialVectorEnv obj's underlying member method code with example usage: obj.test_num_envs() without return types